In data communication, two users who have bilaterally agreed to communicate with each other, but not with other users. Note: Each user can belong to more than one bilateral closed user group and to more than one closed user group by means of outgoing access.; 在数据通信技术中,两个双边同意进行相互通信,但不与其它用户通信的用户。注:每个 用户可通过出网访问功能归属于多个双边封闭用户组和多个封闭用户组。